The Horrible Pyramid was created with Inform and has IFID 51B53CCE-6164-4549-B90B-74043C3387F7. To play a work like this one, you need an interpreter program: many are available, among them Zoom
for Mac OS X and for Unix; Windows Frotz or Windows Glulxe for Windows.
Or you can play without downloading anything by following the 'Play In-Browser'
on your web browser.